Incremental nearest neighbor Producing sorted lists required for FA and TA can be done efficiently by incrementally returning nearest neighbors Incremental NN algorithm follows best-first strategy Assume a tree-based index structure Maintain a min heap of nodes and leaves ordered according to their minimum distances to query Initialize it with the root node Whenever a call for the next nearest neighbor is made   Look at top element of heap   If it is a leaf, return the object and stop   If it is an internal node, delete it, and insert its children